Method for winding torodial power transformers



July 2,01, A., m HALAQSY Mmmm F011 wINDINGL TGRMDAL www TRANSFGRMERS Filed IEGli 5 shears-sheet 1 INVENTOR. ANDREW A. HALACSY ATTORNEY July 20,1965 A. A. HALACSY 3,195,820

METHOD FOR WINDING TOROIDAL POWER TRANSFORMERS Filed July 13. 1961 5 Sheets-Sheet 3 76' FIG. 4

FIG. Il

ANDREW A. HALACSY ATT`ORNEY July 20, 1965 f A. A. HALAcsY 3,195,820

` METHOD FOR WINDING TOROIDAL POWER TRANSFORMERS Filed July 13. 1961 5 Shggfhssheet 4 swf/me Q4) INVENTOR. ANDREW A. HALACSY ATTORNEY July 2o, 1965 A. A. HALACSY 3,195,820

METHOD FOR WINDING TOROIDAL POWER TRANSFORMERS Filed July 15, 1961 5 sheets-sheet 5 FIGJOCI FIG. lOb @2Q M7/eg# #ff/riz FIG. OC FIG. lod

22 22E I l 24 FIG. I0

FIGJOg FIGJO h FIG. lOi a@ 24 mms/T01; ANDREW 'A. HALACSY 22 wd/a@ ATTORNEY United States Patent 3,195,820 METHOD FOR WINDING TURGDIAL PWER TRANSFORMERS Andrew A. Halacsy, Eiizabetll, NJ., assigner to Federal kPacific Electric Company, a corporation of Delaware Filed .luiy 13, 1961, Ser. No. 123,859 9 Claims. (Cl. 242-4) This invention relates to an improved method for winding toroidal power transformers for the distribution of electrical power. So-called pole transformers are an example of what is intended.

Transformers employing cores formed as wound coils of magnetic strip and of generally rectangular shape are commonly used for power distribution. Such transformers are high in electrical efriciency, but practical methods and apparatus have not been available for making toroidal windings on a toroidal core. Currently used transformers use a current-carrying or copper coil that is either prewound or wound in situ on one leg of a wound core, and accordingly it has been necessary to form the core as a modified rectangle with at least one straight saide for the copper coil. Such an arrangement is less efcient in operation and in utilization of copper and iron, and is heavier and bulkier than would be the case if the core were toroidal and had a toroidal conductive winding with a hole in the toroidal core of minimum diameter to accommodate the turns of the toroidal conductive winding.

Small toroidal-core devices having toroidal windings are used in computers and in communications devices; and

somewhat larger toroidal devices have been used as variable-autotransformers. The apparatus for making such windings and the proportions of such devices are both unsuited to application in distribution transformers. Therefore, an object of this invention is in the provision of a novel method for winding toroidal primary and secondary current-carrying coils on a toroidal core in making a distribution power transformer.

In one aspect of the invention there is provided an improved method for placing primary and secondary wind` ings on a toroidal core for use as a distribution power transformer. The method includes the steps of position- ,ingythe core with its central axis lying in a given plane,

preparing a wound length of wire in a form that can be threaded through the aperture in a core, securing the wire to the core, causing a half-turn of rotation of the core relative tothe wound length of wire in a manner to keep the core axis within the given plane, whereby a partialv turn of the wire is formed around the core. The wound length of wire is then passed bodily through the core and another half-turn of relative movement is once again produced between the core and the length of wire. The windring is completed by repeating the alternate steps of threading the wound supply of wire through the core and producing half-turns of core rotation in the manner described. The core is also gradually indexed about its own axis for distributing the turns of wire about the periphery of the core.

For better understanding the invention, including the foregoing and certain additional objects and features of novelty, reference is made to the following detailed deyscription of an illustrative embodiment thereof, which is shown inthe accompanying drawings. In the drawings:

FIG. 1 is a plan view of the novel illustrative transl former winding apparatus;

FIG. 2 is a front elevation view of the apparatus of FIG; 1; FIG. 3 is a right-hand end view of the apparatus of FIG. l with the shuttle conveyor omitted and other parts broken away in the interest of simplicity and clarity;

FIG. 4 is an end view on an enlarged scale and in par- 3,195,820 Patented July 20, 1965 ICC tial section taken along the line 4-4 of FIG. 2, additionally showing a supply of wire used in carrying out a particular method;

FIG. 5 is a plan view on an enlarged scale and in section taken along the line S-.5 of FIG. 3 showing one stage in the winding operation;

FIG. 6 is a view similar to FIG. 5 at a subsequent stage in the winding operation;

FIG. 7 is a cross-section of a portion of the wire placing apparatus taken along the line 7 7 of FIG. 5;

FIG. 8 is a cross-section of the shuttle-supporting apparatus taken along the line 8-8 of FIG. l, shown on an enlarged scale, showing the shuttle in place;

FIG. 9 is a cross-section of the shuttle-supporting apparlatus taken along the line 9 9 of FIG. l on an enlarged sca e;

FIGS. 10a to 10i are a diagrammatic presentation of various phases in the novel winding method; and

FIG. ll is a diagrammatic view of a core and its supporting rollers, representing the progression of turns made by gradual rotation of the transformer core about its central axis.

Referring to the drawings, the toroidal power transformer being wound comprises a core 20 on which one or more turns of wire 22 are shown. Transformers of this type, having other new and useful features, are described in full in my co-pending US. applications Ser. Nos. 47,200 and 47,201 which are assigned to the assignee of this application. An illustrative size of transformer which may be fabricated in accordance with features of this invention has a wound core of silicon steel weighing 787 pounds. The core has an inner diameter of 81/2 inches, an outer diameter of 21%. inches, and a height of 13% inches.

During the manufacturing operation, some 39,260 inches of .108 inch diameter insulated copper Wire are applied in discrete lengths as the primary and secondary windings, the complete transformer having an overall weight of 890 pounds exclusive of mounting, protective and cooling structures. The length of wire would, of course, be divided into the primary and secondary windings as required by the transformer design.

The length and cross-section of wire in a particular winding is determined by the engineering design of the transformer. The method of winding the wire on a core will first be described with reference to FIGS. 10a to 10i. Once the length of wire required for particular winding has been determined, the wire 22 is wound in a configuration capable of being passed through the aperture in the core as for example on a shuttle 24 which, when fully loaded, is able to pass through the aperture of the core with suiicient clearance for previously positioned wires. The free end of the wire 22 is secured to the core as by taping (FIG. 10a) and the shuttle 24 is then fed through the aperture or window in the core 20 (FIG. 10b). The wire is drawn taut against the core by drawing the shuttle away from the core 20 (FIG. 10c). Core 20 :is then rotated Ithrough a half-revolution (FIGS. 10d and 10e). After completion of one lengthwise stroke of the shuttle and a rotation of the core as thus far described, it will be recognized that a full turn has been wound about the core. The wire that initially was angled away from the lower side of the shuttle as illustrated in FIG. 10a assumes a position angled away from the upper side of the shuttle in the illustration of FIG. 10e. A full turn of wire has thus been wound around the core, and a halfturn of wire has been -unwound from the shuttle. Shuttle 24 is reciprocated once again, traveling through the core as shown (FIGS. 101c and 10g). Core 20 is rota-ted through a second half-revolution (FIGS. 10h and 10i), thereby completing a second turn of wire about the core and restoring the parts to the condition shown in FIG. 10a.

' The length of the'shuttle 24 lis such that one 54a. Y Y v .n t v. Platform 32 isV rotated Vby means of main shaft 66,V Y which depends beneath the platform' 4,2 an'd is coaxial with The second stroke of the shuttle (FIGS. 101' and gj followed by the second 180 rotation of the core thuswinds a second turn about the core and unwinds a second halfturn of wireifromV the shuttle. In the'preferred embodifv ment illustrated, the core is rotatedthroughpa' half-turn andthe shuttle reciprocated in alternate feeding androtating steps until the entire length of Wire carried by the'v shuttle has beenV wound, upon` the core. The coreY 20 is kalso gradually rotated about itsrgcentral axis between the strokes of theV shuttle 124; so thatrthesuccessive turns of Wire 22 are placed upon the core 2l) in the desired Yrelation, whether spaced apart, abuttingor overlapping, Aas may be required in the transformer design. r half ,of a loop of wire about the shuttle is, to a close approxi- Yhollow shaft 54. Synchronized rotation of upper core support 52 and Vplatform V42 is accomplished by the followingmechanism,r best shown in FIG. 3. External drive y shaft 63 vis notably supported at its upper endfrom an extension 7) (FIG. l) of bracket 46 and at its lower end Y by a bracket '71 extending from' platform 42. Sprocket 72 aihxed to the main shaft-66, is connected to sprocket 74 ondrive shaft'68 by a chain 76. Sprocket 7 8 on shaft lihas a slot (not shown) contiguous with and connecting to slot 54a in the shaft and is/.connected tothe sprocket Sil on drive shafto by chain 82. Chain 82k is provided with removable links so'that it may beternporarily disassembled to allow wire 22 to be positioned inthe bore of shaft 54'. Drive shaft 6% is rotated by the drive gear armation, equal to a full turn of the winding on the core.V

This may not be exact and consequently it may be necessary to reverse the shuttle lengthwise, i.e.,`turn the-shuttle end-for-end, after a number of strokes of reciprocation in order to keep a reasonablelengthofwireibetweenthe rangement 84 and handle S6.V

Where a short length of wire is involved, wire v22 may bewound upon a single shuttle 2 4. Referring toy FIGS.

' 1 and`8, a typical shuttle 2li-'comprises a pair-of,A opposed shuttle andthe core,V Apart from such occasional.end-for-f end reversals, the only motion ofthe shuttle tis oneV ofV repeated lengthwise reciprocation.

VAn apparatuslcapable of carrying out they stepsof ythe aforedescribed method is shown in FIGS. Vl--9 and 1l.

' .'I he apparatus includes arlower or basesupport 26 for the core 2t?. Support 26 comprises a pair of'opp'osed- 'side frames 28, 3d which are adjustably secured to 'a'rotatable'VVV platform 252.V Coresupporting rollers Mare mounted on shafts 36 which extend in .bearings 38 affixed to thel walls 2.3, Si). Bearings :iS-areV adjustably carried in'slots 39 in frames 2S, Sti so that their position maybe adjusted radially of the center ofthecore to compensate'forvari- Y ouscore sizes without changingfthe position of the rcenter hole or window of the cor-e. One of the'shafts 36 is pro;

vided with a handle 40 whose function will be discussed in greater detail in connection with the operation Vof the apparatus. The separation betweensideframes or Walls 28, 30 is adjustable so that the support 26 may be "ad- Y justed to correspond to 4VVarious core sizes', with clearance for the windings. Y

Platform 32 is rotatably supported Vontable 42 by bearf ings Lili.' Upper support Y46 is carried by posts 48 .secured to` the tablev 42 exteriorly ofthe rotatable platformy 32.

Upper support 46 is removably held on the postsV 48 and is removed when Vloading andV unloading the apparatus.Y

` Rotatable ,core support 52is pivotally mountedV at thel center of the upper support '46 upon a hollow shaft 54': (see FIG.,4). Shaft 54 is fixed to bearing collarV 56 thatv rests on bracket 46 to carry core support 52.Y Y Shaft 54 hasV a slot 54a in line with a like slot (not shown) in bearing 56, so that one position of shaft 54 lines up theslots in I `the turn wound i about the core.

VWhere the amountmof wireV for a winding to'be placed upon the core is greater than ,that which can be accommodated 'byV a single shuttle V.within the. ypreviouslyfY described restrictions,'it Vis of special advantage to employ 'y two shuttles to apply the continuouslength of wire. The

wire is wound upon twok ,shuttles starting from the free ends of the wire'and winding it about the shuttles toward itskmidpo'int. The manner in'which'the two-shuttle method functions asdistin'guished from-the `previously described single YshuttleV methodwill be discussed `in, detail 'f later. :Roller conveyors 92 are provided vto assist in carry- .-'lO

ing'the winding shuttle 24 .toward `and awayfromthe core 20. The shuttle i's moved bysuitable means, asby hand,

toward, through and away from thecore. jlnthe apparatus-shown inthe drawing, theV conveyors 92 comprises `a Vthe shaft andin the bearing collar. A The slot in bearing 56 is contiguous with a slot (not shown) formed r`in the bracket 46. f A slotted shuttle carrier 55 is affixedV to .the

channel frame 94 within which a plurality of rollers 96 are journaled at their ends.` The rollers`v 96 are notched vat 9S to provide clearance for the shuttle 24 (FIG. 8). It is contemplate that power means maybe-used to move the 4shuttle yalong the conveyor 92, either by powering the conveyor or by providing .external means. Y

`Wire snubbers 100, which form the wire 22 against the coreas itVV is wound, are pivotallymounted on the posts 48 (sce FIG.' 7).Y vThese snubbers are constrained to a desiredposition relative Vto the core 20. by torsion springs 'Y W2. Y kSnubber shaft 104 is yslidable. Within 2housing 106 upperend of shaft S4. The slot 55aV in ,shuttle carrier 55 is in line with slot 54a in shaft 54. InV the position shown in FIG. 1 the various slots of the fixed and rotatf r able portion of the apparatus are aligned to form' afpassage 57 from the exterior of the apparatus to the center of shaft S4. y g Y The core supportV 52 includes ,a vpair of channel members 58 which are secured to Va collar 60 carried by shaft yagainst which the torsion Vspring1tl2reacts. Adjustable stops l163 onshaft 104 are provided, to' control the extension of the, shaft'194 androller 119 which is carried at the end'of the shaft-134. ,The shaftlf is maintainedV in 4its extended r,positionby compression spring 112. The

54 with a slot in the collar (not shown)VY aligned with the slotr 54a in the'shaft. The channel membersSS Yare oppositely` disposed aboutjshaft ,54 with theirl longitudinal axis'parallel tothe Vslot 54a in the shaft. Opposedlcore support rollers 62 lare aixed to channel members 58and 1 are adjustable therealong-to allow yfor various core widths. v

The rollers 62are removably securedby bolts 64V tothe channel members 58 so `that a wire22 may be'rpa'ssed betweenthe members 58 into thecenterbore ofthefshaft 'y peripheryl of each roller 11d-is wide .enoughto contact several wireson the core and to roll them'against the core.

The roller may be. of steelbut is advantageously fabricated from Vslightly resilient material as for example'nylon or T eflonlwhich areY relatively rigid plastic materials.

Reference will now-be made to'a typical cycle of operationY ofthe presentmachine,. to facilitate a morefthorough understanding of theinveritiomv In carrying out the Vwinding of a core `20 wit-heither a single' shuttle 24 orA :amdoublef shuttle kMaand-'24h as be later de- Y' scribed, a core is loaded1into the support frame 26. To facilitate this,y onefof the'rollers Maud4 its shaft 36 may f be remoyedjand restored afterthe core is in place.

v The core 20v'is'placed'i the apparatusbetweenthe side plates 28, 30. .The upper kcore supportf46 Vis placedon :the posts 48-with the rollers `62disposed on opposite sides certain transformer configurations.

of the core. Chainr 82 is Vreconnected so that the rotation of the upper and lower core supports 26 and 46 will be synchronized with one another (FIGS. 2 and 3). Lower support 26 and upper support 46 position the core 20 with its central axis (axis of symmetry) lying in a given plane. In thefembodiment shown in the drawings, this plane is a horizontal plane. The core-supporting apparatus is rotatable about a vertical axis, passing through shafts 54 and 66, which is perpendicular to lthe given plane. The upper and lower supports also center the core 20 relative to the vertical axis.

In carrying out the aforedescribed single shuttle method, a predetermined length of wire equivalent to the length of a particular number of turns of a Winding, is wound upon the shuttle 24; (which may be two or more ,shuttlesfjoined end-to-end to achieve the desired wire capacity). The particular number of turns may be equivalent to a complete winding or a portion thereof since several sets of windings may be connected in parallel in While, preferably, half the circumference of the shuttle is substantially equal to the length of a single turn on the core, it may be advantageous to increase the length of the shuttle to reduce the number ofV bends necessarily made in the Wire in preliminarily winding it about the shuttle.

The shuttle 24 is placed on a conveyor as, for example, roller conveyor 92, and the free end of the wire 22 is temporarily secured, as by taping, to the exterior of the core (FIG. a). The end may be connected to a terminal or to another winding later. The shuttle is passed through the core aperture (FIG. 10b) and to the opposite side of the core (FIG. 10c). The core is rotated about its vertical axis 180. The rotation is produced by the drive gears 84 through shaft 68. Shuttle 24 is passed back through the core drawing the wire 22 with it. It is not necessary for the shuttle to be turned end-for-end to either take up the slack in the wire or to pay out addivtional wire. In that event the circumference of the shuttle approximates two turns around the core, or one turn about the core equals approximately the length or half the circumference of the shuttle. However, turning the shuttle end-for-end will either take up the wire or lengthen it as required. The entire wound length of wire is transferred from the shuttle to the core by successive rotations of the core and passes of the shuttle.

Referring to FIGS. 5 and 6, the snubbers 100 form the wire 22 against the core 20 as the core is rotated. Effectively, the wire is passed from one snubber to the next by the rotation of the core. The snubbers maintain the last wound turns in position on the core as the shuttle is reciprocated. The torsion springs 102 (FIG. 7) swing each snubber roller 110 into the path of the core and the compression springs 112 force the roller against the wire yand the wire against the core.

It is advantageous for the core to be rotated step-wise about its central axis between reciprocations of the shuttle so that succeeding turns of the wire may be placed on the core'adjacent the previously wound turn. This is accomplished by means of one of the supporting rollers 34 which frictionally engages the core as can be seen in FIG. 1l. The core is revolved about its central axis a peripheral distance equivalent to the width of the Wire. This movement may occur either intermediate the rotation of the core about the vertical axis of the apparatus or simultaneously therewith. The reciprocating movements of the shuttle intermediate the step-wise 180 rotation of the core (FIGS. 10a to i) are continued with the Wire being laid against the core in a desired configuration, until the length of wire Wound on the shuttle has been exhausted. The end of the Wire is then temporarily taped to the core. Subsequent windings may be positioned on the core by repetition of the single-shuttle method previously outlined above and may be connected to either the previously wound turns or to a terminal. The wound core is removed from the apparatus by reversing the loada ing procedure described above.

In some circumstances, the length of wire to be wound for a particular winding must be in one piece and is such that it is most advantageous to employ two shuttles. In the two-shuttle method, the length of wire is Wound upon two shuttles starting from the free ends of the wire and winding toward the center thereof. The core is positioned as before and the rst or A shuttle 24a is positioned in carrier S5 (FIG. 4) on shaft 54. The slots in the carrier 55, shaft 54, collar 56, sprocket 78, yoke support bushing 60, are aligned and a core support roller 62 and sprocket chain S2 are removed and the Wire 22 is led through the slots. The sprocket chain 82 and the core support roller 62 are then replaced. The B or second shuttle (not shown) is placed on the conveyor 92 and passed through the core aperture. The Wire 22 is then taped to the core Ztl where it passes through the aperture and the winding operation proceeds as previously de. scribed for the single shuttle method. The A shuttle 24a, carrier 55, support 52, and core 20 rotate together therefore no twisting of the wire occurs between the shuttle and the core. When the B shuttle is exhausted, the A shuttle is then employed to finish the winding. The shuttle is removed from the carrier 55 by passing the wire through the various aligned slotted members once the sprocket chain 76 and core support roller 62 have been removed. It' the B shuttle has been wound onto the core with a clockwise rotation of the core then the A shuttle is wound on the core in a counter-clockwise direction so that the turns remain in their proper relative position on the core. The core is rotated about its central axis during the Winding so that subsequent turns may be placed next to one another in a spiral, serial manner. When the B shuttle has been emptied and the free end taped to the core, the taped midpoint is returned to the starting position and the core rotated in the reverse direction for the A7 shuttle.

The method, and apparatus for carrying out the method herein described, allow, for the first time, the production of distribution power transformers having toroidal cores.

Although several embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that various changes and modilications may be made therein without departing from the spirit of the invention.

What I claim is:

1. A method of winding a power transformer having a core with a central axial aperture comprising the steps of positioning the core with its central axis lying in a given plane, preliminarily winding a length of wire into a con- Afiguration capable of being passed through the central aperture in said core, securing a portion of said wire against movement relative to said core, rotating said core through substantially one-half of a revolution about an axis normal to said given plane, drawing said Wire taut whereby said wire is drawn against said core, passing said wound length of wire through said core, rotating said core in the same direction through substantially one-half a revolution once again, and repeating said alternate passing and rotating steps until said wire has been wound about said core forming a winding thereon.

2. A method of winding a power transformer having a core with a central axial aperture comprising the steps of positioning the core with its central axis lying in a given plane, preliminarily winding a length of wire into a pair of joined configurations each capable of being passed through the aperture in said core, securing said wire to said core intermediate said configurations thus creating wound first and second half lengths, rotating said core relative to said first half of said Wound length whereby said wire is drawn against said core, passing said first half of said wound length of wire through said core, rotating said core relative to said rst half of said length of Wire `V. .i Y i i ."v' v l" 'once again, repeating said alternaterfeeding and riatlflg steps until said Vlirst halt ofsaid wire length has been wound about said core forming a partial Vwinding thcre'- Y l on, rotating said core relative to saidV secondv half of said` wound length, passing saiddsecond half of said' length'V of wire through said core, rotating said 'core relative to said second half of said wound length,`and repeating said alternate passingand rotating steps until said second halt 'of said wound length of wire has been wound about said core thereby completing said previously partial winding thereon. Y

E5.V VA method o1` windingapower transformer having a.

core with a central axial aperture comprising the Vsteps of y positioning the core with its central axis lying in :aj given plane, securing one portion of awoundV length of wire to said core, passing said wound length of wire through theY positioning the core with its central axis lying in a `given'V plane, securing a portion ofjra wound length ofvire ofra given diameter tov said core, passing said wound Vlength through the aperture in said core thereby threading said wire through said core, rotating said core 180 about an axis normal to said given plane, arngularlyV indexing saidV core about its central axis a distance substantiallyV equal to said given diameter of said wire, again passing said,y

wound length of wire through said core and therebeyond "Si t f du'ctorythrough;saidrraperture in` alternate traverse and return reciprocating strokes, rotating said core approxirnately 180" aboutan axisl perpendicular to the axis of its .own aperture Vand perpendicular to the path of said shuttler intermediate saidY strokes, and progressively indexingsaid core. about the yaxis of its aperture, whereby Y ,the conduct-orrisfwoundon saidcore forming a winding thereon. 1 Y' t i Y ,18. ,A lrnethcxi vot" winding a power transformer having Va 'core with a central "aperture comprising t-he stepsv of fsecuring .one lportionof a length of Wire to the core, another'p'ortionofthe wire being supported on'an elongated shuttle andwound in therform of a coil whose turns extend along the shuttle and around its; ends, passing said shuttle in a ilengthwise'stroke through the aperture in said core Vthereby threading saidfwire` through said core, ro

Y vtating sai-d core through Iapproxirnaftely oneshalf 'of a revolutionV about an axis .transverseto 'the plathof the shuttle, whereby said wire is drawnagainstsaid core, vpassing said shuttle in another lengthwise strokethrlough the core to its original position, rotating said vcoreonce again through 'y :approximately one-half of a revolution inthe same direction als before to, Wind Vthe 4wire; -onthe core, and p.,- riodically reversingl the shuttleV end -fror-e'nd between said lengthwise' strokes. y Y Y 9,. A methodfof Wind-ingle power; transformer having an annular .core `with, a centra-lV aperture, including the steps of winding a length oftwire linto two integnally `int terconnected coils :each of,V which is elongated yand has whereby said wire is drawn against said core, again r'otat-V ing'said core 180, and repeating said passing and said 180 rotating and said angular indexing stepsluntil said g wound length of wire has been wound about's'aid core forming a winding thereon.,

5. A method of winding apower cludes a corehaving a cent-nal aperture comprising the steps of securingk a portion of a length Vof wire against Y .40 transformer that int strokes .of reciprocation through said aperture and indexing lsaid corethrough a half-revolution between each stroke of the coil and the next stroke, rthereby to 'wind successive turns of Wire on said core.

6. A method of winding a power transformer'having an lannular core with an aperture including the steps of .fixing aportion of a conductor against movement-relative to said core, reciprocating Ia relatively long and slender shuttle Wound along itsrsides and about its Yends with said vconductor through said aperture in alternatetraverse land'return reciprocating strokes, and relativelyfurotating said core and said shuttle intermediateisaid strokes about 4 an axis normal towthat of said annular core whereby the.

conductor is wound on ysaid core fior-ming Va Winding"v thereon. i

7. A method of winding a power transformer having la i central axial aperture including t-hesteps of fixing a por-r tion of a conductor Aagainst movement relative to said core, reciprocating a relatively 'long yand slender shuttle wound yalong its sides and about its endsk with thel con#k its turns extending along its length and around its Vends, securing the portion of; said `wire thatinteroonnects said `Coils*V against movement relative to said core, reciprocating one of said` coils'rlengthwise through ,said aperture in alternate-traverse and return strokes, rotating said core approximately,180between eachreciprocating stroke of saidiooil as aforesaidand the next stroke, the rotation of the core being about an'` axis .penpendicular to that of the annular core and perpendicular to the path of reciprocationjand continuing therceiprocating strokes and the 180 rotations in alternation until the. first elongated Vwinding hasbeen wound about vthe croire, the second elongated coil being rotatable witbu'the core during the aforementioned 180 rotations, and thereafter alternately reciproeating thesecond coil through the aperture of the core and rotating the corein 180"V increments as .aforesaid until the wire tormingthe second elongated coil has been wound-about said core. .n 1 i l References Cited bythe Examiner Y UNITED srAras PATENTS 2,102,692 12v/37 gil-"inanz' l *242-4 2,313,306 n 3/43 Wiegand' 29-155.57 2,344,006 Y 3/44 ySteinrnayer 29-155.57 2,640,652' 6/5-3* Harvey 242-1.1 Y y2,819,850, 1/58 Yivrathis, 242-4 12,820,598 ,-l/58 Aveni 242-4 #2,921,751 i1/60 Aveni 242-4 Y l2,962,255 Ylil/60 Ridler et al.f 242--4 Y2,991,021 Y 'v7/6:1 Batty 242-1.1

Y N'FOREIGN PATENTS ,345,67797, 12A/2,1Germany.kv

SllElN, Prriirzry Examiner. 1 nAaarSoN a. MOSELEY, Emm'ner.` 

5. A METHOD OF WINDING A POWER TRANSFORMER THAT INCLUDES A CORE HAVING A CENTRAL APERTURE COMPRISING THE STEPS OF SECURING A PORTION OF A LENGTH OF WIRE AGAINST MOVEMENT RELATIVE TO THE CORE, THE WIRE BEING IN THE FORM OF AN ELONGATED COIL WHOSE TURNS EXTEND ALONG THE COIL AND AROUND ITS ENDS, AND PASSING SAID COIL IN LENGTHWISE STROKES OF RECIPROCATION THROUGH SAID APERTURE AND INDEXING SAID CORE THROUGH A HALF-REVOLUTION BETWEEN EACH 